In a conventional embroidery machine as shown in FIG. 1, a beam 102 at upper part of a work table 100 is provided between both end portions of the work table 100, and multiple heads having a plurality of needles are disposed along the beam 102 in identical interval.
Further, an upper shaft 106 for driving thread take-up levers (not shown) is provided in the lateral direction through the plurality of heads 104. A lower shaft 108 for rotating hooks (not shown) is provided in the lateral direction at lower part of the work table 100. The upper and lower shafts are supplied with power from a driving motor 110 disposed at lower part of one end portion of the work table 100 in order to drive the rotating hooks and needle bars for performing embroidery tasks.
Generally, each of the heads has nine needle bars, where one needle bar is intended to correspond to one color. Each of the heads is not driven with control of a central control unit, but each of the heads is typically driven with ON/OFF switch provided thereat. When an operator drives the switch, a head control signal is transferred to head control unit, and then the head is driven according to the control signal of the head control unit.
However, because such types of the conventional multi-head embroidery machines are limited in number of the needle bars provided at the heads as described above, the colors of embroidery available to one multi-head embroidery machine are limited in their number. As a result, only 9 to 12 colors have been used in the related industry. However, it is a problem that the limitation of the colors can not provide enough colors to attain multi-colored embroidery design required by operators.
To solve the problem, products of embroidery machines that have more numbers of the needle bars provided at one head have been proposed. However, in the proposed products, the size of the heads is too increased to effectively operate the embroidery machine. And also, the proposed products have other problems to increase cost of manufacturing the embroidery machine.
Further, in case of requiring a wide range of embroidery, the embroidery task have to be performed beyond the range of the adjacent heads, so that the adjacent heads are forced to be stopped for the purpose of performing a desired embroidery task. As a result, in this case, the operator has to directly operate the ON/OFF switch to stop the drive of the adjacent heads for the purpose of performing the desired embroidery task. It is inconvenient that after the desired embroidery task, the operator has to drive the stopped heads again using the switch for the purpose of performing the next embroidery task.